Public fears of widespread venereal disease led in 1913 to the appointment of The Royal Commission on Venereal Diseases (RCVD). In 1916 its Final Report offered only a single cautious and somewhat imprecise summary statement about the likely prevalence of venereal diseases in England and Wales. Although the significance of contemporary attitudes to venereal disease has attracted a good deal of historiographic attention, no historian or demographer has since investigated this aspect of the Royal Commission's work. This article critically re-examines the most important quantitative evidence presented to the Royal Commission relating to the years immediately prior to the First World War. It utilises this evidence to produce new estimates of the probable prevalence of syphilis among adult males, both nationally and among certain geographical divisions and social groups in the national population; and also to offer a comment on the likely prevalence of gonorrhoea.